Add sin and cos to functions module
Add sin and cos to functions module

wkentaro/chainer,benob/chainer,niboshi/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,AlpacaDB/chainer,kuwa32/chainer,kikusu/chainer,kashif/chainer,t-abe/chainer,okuta/chainer,woodshop/complex-chainer,kiyukuta/chainer,t-abe/chainer,minhpqn/chainer,anaruse/chainer,okuta/chainer,benob/chainer,hvy/chainer,chainer/chainer,cupy/cupy,ronekko/chainer,jnishi/chainer,niboshi/chainer,jnishi/chainer,wkentaro/chainer,ktnyt/chainer,ysekky/chainer,chainer/chainer,muupan/chainer,keisuke-umezawa/chainer,cemoody/chainer,jnishi/chainer,hvy/chainer,pfnet/chainer,yanweifu/chainer,tigerneil/chainer,Kaisuke5/chainer,okuta/chainer,cupy/cupy,ktnyt/chainer,tscohen/chainer,laysakura/chainer,niboshi/chainer,ytoyama/yans_chainer_hackathon,wkentaro/chainer,wavelets/chainer,hidenori-t/chainer,sinhrks/chainer,cupy/cupy,woodshop/chainer,okuta/chainer,hvy/chainer,aonotas/chainer,delta2323/chainer,1986ks/chainer,wkentaro/chainer,truongdq/chainer,muupan/chainer,niboshi/chainer,jnishi/chainer,keisuke-umezawa/chainer,chainer/chainer,ktnyt/chainer,tkerola/chainer,hvy/chainer,sinhrks/chainer,kikusu/chainer,chainer/chainer,rezoo/chainer,cupy/cupy,masia02/chainer,sou81821/chainer,truongdq/chainer,umitanuki/chainer,ikasumi/chainer,ktnyt/chainer,AlpacaDB/chainer